From: Chen Huang chenhuang5@huawei.com
[ Upstream commit f766f77a74f5784d8d4d3c36b1900731f97d08d0 ]
When a function doesn't have a callee, then it will not push ra into the stack, such as lkdtm_BUG() function,
addi sp,sp,-16 sd s0,8(sp) addi s0,sp,16 ebreak
The struct stackframe use {fp,ra} to get information from stack, if walk_stackframe() with pr_regs, we will obtain wrong value and bad stacktrace,
[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8 ---[ end trace 18da3fbdf08e25d5 ]---
Correct the next fp and pc, after that, full stacktrace shown as expects,
[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8 [<ffffffe0008b24a4>] lkdtm_do_action+0x14/0x1c [<ffffffe00066c372>] direct_entry+0xc0/0x10a [<ffffffe000439f86>] full_proxy_write+0x42/0x6a [<ffffffe000309626>] vfs_write+0x7e/0x214 [<ffffffe00030992a>] ksys_write+0x98/0xc0 [<ffffffe000309960>] sys_write+0xe/0x16 [<ffffffe0002014bc>] ret_from_syscall+0x0/0x2 ---[ end trace 61917f3d9a9fadcd ]---
Signed-off-by: Chen Huang chenhuang5@huawei.com Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Palmer Dabbelt palmerdabbelt@google.com Stable-dep-of: 5c3022e4a616 ("riscv: stacktrace: Fixup ftrace_graph_ret_addr retp argument") Signed-off-by: Sasha Levin sashal@kernel.org --- arch/riscv/kernel/stacktrace.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index 39cd3cf9f06b..3d1e184e39e9 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -63,9 +63,15 @@ static void notrace walk_stackframe(struct task_struct *task, /* Unwind stack frame */ frame = (struct stackframe *)fp - 1; sp = fp; - fp = frame->fp; - pc = ftrace_graph_ret_addr(current, NULL, frame->ra, - (unsigned long *)(fp - 8)); + if (regs && (regs->epc == pc) && (frame->fp & 0x7)) { + fp = frame->ra; + pc = regs->ra; + } else { + fp = frame->fp; + pc = ftrace_graph_ret_addr(current, NULL, frame->ra, + (unsigned long *)(fp - 8)); + } + } }